Gas turbines include, but are not limited to, gas turbine power generation equipment and gas turbine aircraft engines. A gas turbine includes a core engine having a high pressure compressor to compress the air flow entering the core engine, a combustor in which a mixture of fuel and the compressed air is burned to generate a propulsive gas flow, and a high pressure turbine which is rotated by the propulsive gas flow and which is connected by a larger diameter shaft to drive the high pressure compressor. A typical front fan gas turbine aircraft engine adds a low pressure turbine (located aft of the high pressure turbine) which is connected by a smaller diameter coaxial shaft to drive the front fan (located forward of the high pressure compressor) and to drive an optional low pressure compressor (located between the front fan and the high pressure compressor). The low pressure compressor sometimes is called a booster compressor or simply a booster.
The fan and the high and low pressure compressors and turbines have gas turbine blades each including an airfoil portion attached to a shank portion. Rotor blades are those gas turbine blades which are attached to a rotating gas turbine rotor disc. Stator vanes are those gas turbine blades which are attached to a non-rotating gas turbine stator casing. Typically, there are alternating circumferential rows of radially-outwardly extending rotor blades and radially-inwardly extending stator vanes. When present, a first and/or last row of stator vanes (also called inlet and outlet guide vanes) may have their radially-inward ends also attached to a non-rotating gas turbine stator casing. Counterrotating "stator" vanes are also known. Conventional gas turbine blade designs typically have airfoil portions that are made entirely of metal, such as titanium, or are made entirely of a composite. The all-metal blades, including costly wide-chord hollow blades, are heavier in weight which results in lower fuel performance and require sturdier blade attachments, while the lighter all-composite blades are more susceptible to damage from bird ingestion events. Known hybrid blades include a composite blade having an airfoil shape which is covered by a surface cladding (with only the blade tip and the leading and trailing edge portions of the surface cladding comprising a metal) for erosion and bird impact reasons. The fan blades typically are the largest (and therefore the heaviest) blades in a gas turbine aircraft engine, and the front fan blades are the first to be impacted by a bird strike.
Steam turbines include, but are not limited to, steam turbine power generation equipment. A steam turbine includes a steam inlet, a turbine, and a steam outlet, wherein steam turns the turbine rotor. The turbine of a steam turbine is similar to the turbine of a gas turbine. Steam turbine blades, which are generally identical to gas turbine blades, each include an airfoil portion attached to a shank portion. Rotor blades are those steam turbine blades which are attached to a rotating steam turbine rotor disc. Stator vanes are those steam turbine blades which are attached to a non-rotating steam turbine stator casing. Typically, there are alternating circumferential rows of radially-outwardly extending rotor blades and radially-extending stator vanes, wherein the stator vanes radially extend between, and are attached to, radially outer and inner rings. Conventional steam turbine blade designs typically have airfoil portions that are made entirely of metal. The all-metal blades are costly and heavy in weight which results in higher steam turbine prices and which requires sturdy blade attachments.
What is needed is a lighter-weight steam turbine blade.